Combustor controller

ABSTRACT

A turbine inlet temperature operating section ( 15 ) determines the turbine inlet temperature T 4  based on the flow rate Gf and temperature Tf of fuel being supplied to a combustor ( 3 ) and the flow rate G 3  and temperature T 3  of air. Based on the turbine inlet temperature T 4 , a pilot ratio operating section ( 16 ) sets a pilot ratio, and a bypass valve operating section ( 17 ) and an IGV opening operating section ( 18 ) generate a bypass valve control signal and an IGV control signal, respectively.

TECHNICAL FIELD

The present invention relates to a combustor controller of a gasturbine, and especially, relates to a combustor controller whichcontrols a fuel-air ratio of fuel and air being supplied to a combustor.

BACKGROUND ART

Conventionally, a combustor which is provided with a pilot nozzleperforming diffusion combustion with a pilot light by diffusing fuel gasand a main nozzle performing premixed combustion by mixing air with fuelis employed as a combustor of a gas turbine plant. A gas turbine rotatesby utilizing combustion gas from this combustor, and then a generatorgenerates electricity by a motive power of this gas turbine.Consequently, in a power generating facility utilizing a gas turbine, itis possible to control output of a generator by controlling combustionof a combustor.

In controlling combustion of such a combustor as is described above, afuel ratio of pilot fuel being supplied to the pilot nozzle versus mainfuel being supplied to the main nozzle is also controlled. Bycontrolling this fuel ratio to be an appropriate value, it is possibleto restrain exhaust amount of NOx. FIG. 6 shows a construction of thisconventional combustor controller for controlling a combustor which isequipped with a pilot nozzle and a main nozzle.

A combustor controller 100 in FIG. 6 generates based on an output of agenerator 4 a bypass valve control signal, in order to control theopening of a combustor bypass valve 8, which is determined by a bypassvalve opening operating section 102, and supplies the signal to acombustor bypass valve 8, so as to control an amount of air beingsupplied to a combustor 3. Further, this combustor controller 100generates based on an output of a generator 4 an IGV control signal, inorder to control an opening of an inlet guide vane (IGV) 5, which isdetermined by an IGV opening operation section 103, and supplies thesignal to the IVG 5, so as to control an amount of air being supplied toa compressor 1. Here, the bypass valve opening operating section 102 andthe IGV opening operating section 103 calculate values of a bypass valvecontrol signal and an IGV control signal based on the graphs in FIG. 3and FIG. 4. The axes of abscissas in FIG. 3 and FIG. 4 represent anoutput of a generator.

Further, the combustor controller 100 generates a fuel flow rateinstruction signal (CSO) by obtaining a difference between an output ofthe generator 4 and an aimed generator output in a subtraction section 9and then adding thereto an integral constituent in PI section 10. Whenthe value of this CSO from the PI section 10 is compared with apredetermined value “L” by using a limiter 11 and is determined to belower than the predetermined value “L,” the CSO's are supplied to apilot ratio operating section 101 and a multiplication section 12.

In the pilot ratio operating section 101, a multiplication value used inthe multiplication section 12 is set in the multiplication section 12based on CSO so as to be supplied to the multiplication section 12. Inthe multiplication section 12, the CSO being supplied by a limiter 11 ismultiplied by the multiplication value being supplied by the pilot ratiooperating section 101, so as to generate a pilot fuel control signal,which is to be supplied to a pilot fuel control valve 7. Additionally,in a subtraction section 13, a pilot fuel control signal being suppliedby the multiplication section 12 is subtracted from the CSO beingsupplied by the limiter 11, so as to generate a main fuel controlsignal, which is to be supplied to a main fuel control valve 6. Further,in the pilot ratio operating section 101, a value of a pilot fuelcontrol signal is obtained based on a graph in FIG. 2. Moreover, theaxis of abscissas in FIG. 2 represents a CSO value.

In a combustor controller 100 constructed as described above, when aload to a gas turbine 2 is low and an output of a generator 4 is low, inorder to restrain combustion vibration and achieve stable combustion, anopening of an IGV 5 is closed so as to decrease the flow rate of airflowing into a compressor 1, and an opening of a combustor bypass valve8 to increase the flow rate of compressed air flowing directly into thegas turbine 2 from the compressor 1. By decreasing the flow rate of airto the combustor 3 in the above-mentioned manner, a fuel-air ratio isincreased. Moreover, when a load to a gas turbine 2 is high and anoutput of the generator 4 is high, in order to restrain a dischargeamount of NOx, the flow rate of air flowing into the compressor 1 isincreased by opening the IGV and an amount of compressed air flowingdirectly into the gas turbine 2 from the compressor 1 is decreased byclosing the combustor bypass valve 8. By increasing the flow rate of airbeing supplied to the combustor 3 in the above-mentioned manner, thefuel-air ratio is decreased.

Further, when an output from a generator is low, in order to activatecombustion of a pilot nozzle and restrain combustion vibration, therebyachieving stable combustion, a ratio of pilot fuel (“pilot ratio”)versus entire fuel being supplied to the combustor 3 is increased byclosing the main fuel control valve 6 and opening the pilot fuel controlvalve 7. Also, when an output from a generator is high, in order torestrain combustion of a pilot nozzle and restrain the exhaust amount ofNOx, the pilot ratio is decreased by opening the main fuel control valve6 and closing the pilot fuel control valve 7.

Conventionally, a thermal energy obtained by combustion is converted toa kinetic energy by a gas turbine 2 and this kinetic energy is convertedto an electric energy by a generator 4 in the above-mentioned manner.Also, as described above, the output of the generator 4 shows a statewhich is close to a combustion state in the combustor 3, and responsedelay to a change of combustion state in the combustor 3 is small.Consequently, as explained above, conventionally, the pilot ratio andthe opening of an IGV 5 and combustor bypass valve 8 are set based on anoutput from a generator 4.

However, because in a conventional combustor controller, a flow rate ofair being supplied to a combustor and a flow rate of fuel being suppliedto a pilot nozzle and a main nozzle are set based on an output of agenerator, accurate control cannot be performed in a case where a powerfactor of electricity supply system of a generator is changed or in acase where a compound power generation system using a steam turbine atthe same time is subject to a rapid load fluctuation.

Namely, in a case where reactive power is increased, resulting invariation of power factor, proportionality relation between a propulsiontorque of a gas turbine obtained by combustion and the generator outputis broken because the generator output is measured by effective electricpower. At this time, because the generator output becomes small althoughthe propulsion torque of a gas turbine does not vary, such a control isperformed as increases the pilot ratio and the fuel-air ratio.

Moreover, in a compound power generation facility where a steam turbineis connected to a gas turbine by way of one shaft, the generator outputis equivalent to a total of a propulsion torque of a gas turbine and apropulsion torque of a steam turbine. Therefore, the generator outputbased on the propulsion torque of a gas turbine is obtained by presuminga propulsion torque of a steam turbine in a steady state, and the pilotratio and the fuel-air ratio are controlled in the combustor based onthe generator output which is equivalent to this obtained propulsiontorque of a gas turbine. Consequently, the generator output beingequivalent to a propulsion torque of a gas turbine is not obtainedaccurately, and when a rapid load fluctuation occurs, it is impossibleto control the pilot ratio and the fuel-air ratio in the combustoraccurately.

In order to prevent the above-mentioned problem, it is preferable tocontrol the pilot ratio and the fuel-air ratio in a combustor bytemperature of combustion gas at the outlet of the combustor (i.e.temperature of combustion gas being supplied to the inlet of a gasturbine, which is referred as “turbine inlet temperature” hereafter).However, in recent gas turbines, because the turbine inlet temperatureexceeds 1500° C., there exist no temperature-measuring devices which canmeasure the turbine inlet temperature continuously for a long time.Moreover, although there is a method of presuming the turbine inlettemperature by calculating from the casing pressure of a combustor andexhaust gas temperature of a gas turbine, response of exhaust gastemperature to combustion state is bad. As a result, a delayed value issupplied to the actual turbine inlet temperature, which causes aresponse delay to occur in controlling the pilot ratio and fuel-airratio in the combustor.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a combustorcontroller which can calculate a turbine inlet temperature accuratelywithout response delay and also can control a combustor based on theturbine inlet temperature which results from calculation.

In order to achieve the above-mentioned object, according to the presentinvention, a combustor controller, which is mounted to a gas turbinebeing installed by sharing a same shaft of a generator and controls acombustor by supplying combustion gas to the gas turbine so as to rotateit, is provided with:

a fuel flow rate operating section which sets a flow rate of fuel beingsupplied to the combustor based on a differential value between anoutput of the generator and an aimed output of the generator;

a turbine inlet temperature operating section which obtains a turbineinlet temperature serving as a temperature of combustion gas flowingfrom the combustor into the gas turbine, based on the flow rate and thetemperature of fuel and air flowing into the combustor, respectively;

a pilot ratio operating section which sets the pilot ratio serving asthe ratio of a pilot fuel being supplied to a pilot nozzle inside thecombustor and performing diffusion combustion of a pilot light versusentire fuel flow rate, totalizing the pilot fuel and a main fuel beingsupplied to a main nozzle inside the combustor and performing premixedcombustion by mixing air and fuel, based on a turbine inlet temperatureobtained by the turbine inlet temperature operating section; and

an air flow rate calculation section which sets the flow rate of airflowing into the inside of the combustor, based on the turbine inlettemperature determined by the turbine inlet temperature operatingsection; and is characterized by:

wherein, flow rates of the pilot fuel and the main fuel are controlledbased on the pilot ratio obtained by the pilot ratio operating sectionand the fuel flow rate obtained by the fuel flow rate operating section;and

wherein, combustion state of the combustor is controlled by controllinga flow rate of air flowing into the inside of the combustor by the airflow rate obtained by the air flow rate operating section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a construction of a gas turbine powergeneration facility provided with a combustor controller in accordancewith an embodiment of the prevent invention;

FIG. 2 is a graph showing a relation between a pilot ratio and a turbineinlet temperature or CSO;

FIG. 3 is a graph showing a relation between an opening of a combustorbypass valve and a turbine inlet temperature or a generator output;

FIG. 4 is a graph showing a relation between an opening of an IVG and aturbine inlet temperature or a generator output;

FIG. 5 is a diagram depicting an example of a inner construction of aturbine inlet temperature operating section; and

FIG. 6 is a block diagram showing a construction of a conventional gasturbine power generating facility.

BEST MODE FOR CARRYING OUT OF THE INVENTION

Referring now to the drawings, an embodiment of the present inventionwill be described hereinafter. FIG. 1 is a block diagram showing aconstruction of a gas turbine power generating facility provided with acombustor controller in accordance with an embodiment of the presentinvention. Here in FIG. 1, same symbols will be supplied to a sameportion as in FIG. 6 and their detailed explanations will be omitted.

A gas turbine power generating facility in FIG. 1 is provided with acompressor 1 equipped with an IGV 5 which serves as a stationary bladein a first stage; a gas turbine 2 which is provided to a same shaft ofthe compressor 1; a combustor 3 which supplies combustion gas so as torotate the gas turbine 2; and a generator 4 which is rotated by rotatingthe gas turbine 2 so as to generate electricity. Additionally, areprovided a main fuel control valve 6 which sets a flow rate of fuelbeing supplied to a main nozzle (not illustrated) of the combustor 3; apilot fuel control valve 7 which sets a flow rate of fuel being suppliedto a pilot nozzle (not illustrated) of the combustor 3; a combustorbypass valve 8 which sets a flow rate of air bypasseing from thecompressor 1 to the gas turbine 2 so as to determine a flow rate of airbeing supplied to the combustor 3; and a combustor controller 20 whichcontrols a fuel-air ratio and pilot ratio of the combustor 3.

Further, in order to measure a fuel flow rate Gf and a fuel temperatureTf of fuel to the combustor 3 respectively, are provided a flow-ratemeasuring device 21 and a temperature-measuring device 22 that aremounted before a branch connection in a passageway for fuel supply,which supplies fuel to a main nozzle and a pilot nozzle, respectively; atemperature-measuring device 23 which is mounted at the outlet of acompressor 1 so as to measure a temperature T3 of compressed air beingdischarged from the compressor 1; and a differential-pressure-measuringdevice 24 which is mounted before and after the IGV 5 of the compressor1 so as to measure the differential pressure Pd of air flowing into thecompressor 1.

When a gas turbine power generation facility is constructed as describedabove, an amount of air flowing into a compressor 1 is set by an openingof an IGV, and also an amount of air flowing into the combustor 3 fromthe compressor 1 is set by a combustor bypass valve 8. Then, when aircompressed in the compressor 1 is supplied to the combustor 3, not onlydiffusion combustion is performed by a pilot nozzle to which fuel issupplied by way of a pilot fuel control valve 7, but also premixedcombustion is performed by a main nozzle to which fuel is supplied byway of a main fuel control valve 6. In consequence, high temperaturecombustion gas obtained as a result of burning in the combustor 3 issupplied to a gas turbine 2. When the gas turbine 2 is rotated bycombustion gas being supplied by the combustor 3, a generator 4 sharinga same shaft is rotated, too, so that the generator 4 generateselectricity and outputs electric power.

At this time, the flow rate Gf of entire fuel being supplied to thecombustor 3 is measured by a flow-rate-measuring device 21 and also, thetemperature Tf thereof is measured by a temperature-measuring device 22.Additionally, a temperature T3 of air being supplied to the combustor 3from the compressor 1 is measured by the temperature-measuring device23. Further, a differential pressure Pd of air flowing into thecompressor 1 is measured by a differential-pressure-measuring device 24.Then, the fuel flow rate Gf, fuel temperature Tf, air temperature T3,differential pressure Pd and an opening k of a combustor bypass valve 8that are measured are provided to the combustor controller 20.

Then, the fuel-air ratio and pilot ratio of a combustor 3 are set by acombustor controller 20, based on the fuel flow rate Gf, fueltemperature Tf, air temperature T3, differential Pd and opening k of acombustor bypass valve 8. Consequently, an IGV control signal, a mainfuel control signal, a pilot fuel control signal and a bypass valvecontrol signal, respectively, are generated based on the fuel-air ratioand the pilot ratio that are set, so as to be provided to an IGV 5, amain fuel control valve 6, a pilot fuel control valve 7 and a combustorbypass valve 8.

This combustor controller 20 is provided with: a subtraction section 9that receives output E0 of a generator 4 and calculates the differentialvalue E1−E0 thereof from an aimed output E1 is obtained; a PI section 10which generates a CSO by adding an integral constituent to thedifferential value E1−E0 obtained by the subtraction section 9; alimiter 11 which supplies a CSO serving as “L” when the value of CSOfrom PI section 10 is larger than “L;” a multiplication section 12 whichgenerates a pilot fuel control signal by being supplied with a CSO fromthe limiter 11; a subtraction section 13 which generates a main fuelcontrol signal by subtracting a value of a pilot fuel control signalwhich is supplied by the multiplication section 12 from a value of CSOwhich is supplied by the limiter 11: an air flow rate operating section14 which determines a flow rate G3 of air flowing into the combustor 3based on a differential pressure Pd and an opening k of a combustorbypass valve 8; a turbine inlet temperature operating section 15 whichobtains a turbine inlet temperature T4 based on a fuel flow rate Gf,fuel temperature Tf, air flow rate G3 and air temperature T3; a pilotratio operating section 16 which calculates a pilot ratio based on aturbine inlet temperature T4 so as to be supplied to the multiplicationsection 12; a bypass valve opening operating section 17 which generatesa bypass valve control signal based on a turbine inlet temperature T4;and an IGV opening operating section 18 which generates an IGV controlsignal based on the turbine inlet temperature T4.

In a combustor controller 20 being constructed as described above, whenan output E0 from a generator 4 is supplied to a subtraction section 9,an actual output E0 is subtracted from an aimed output E1 of thegenerator 4 and a differential value E1−E0 is determined. In order tomake responsive characteristic satisfactory for this differential valueE1−E0, CSO is generated by having an integral constituent added to a PIsection 10 and is supplied to a limiter 11. In the limiter 11, the CSOvalue is compared with “L,” and when the CSO is smaller than “L,” CSO isoutput from the PI section 10 as it is; whereas, CSO being equivalent to“L” is output when the CSO is larger than “L.”

Additionally, when a differential pressure Pd between inner pressure andouter pressure of an IGV 5 being measured by adifferential-pressure-measuring device 24 and an opening k of acombustor bypass valve 8 are supplied to an air flow rate operatingsection 14, a flow rate G3 of air being supplied to the combustor 3 froma compressor 1 by way of the combustor bypass valve 8 is obtained. Then,together with the air flow rate G3 determined by this air flow rateoperating section 14, a fuel flow rate Gf, a fuel temperature Tf and anair temperature T3 measured by a flow-rate-measuring section 21 andtemperature-measuring sections 22 and 23, respectively, are supplied toa turbine inlet temperature operating section 15. In the turbine inlettemperature operating section 15, a turbine inlet temperature T4 isdetermined based on a transfer function expressed by a formula (2) whichis obtained from a formula (1).Cp4 Vcb γ4×(dT4/dt)=Cpf Gf Tf+Cp3 G3 T3+η Hf Gf−Cp4 G4 T4  (1)T4(s)=(Cpf Gf(s)Tf(s)+Cp3 G3(s) T3(s)+η Hf Gf(s)) /Cp4 G4(s)+Cp4 Vcb γ4s)  (2)

Where, Cp3 is a specific heat of a casing of a combustor 3; Cp4 is aspecific heat of combustion gas; Cpf is a specific heat of fuel; η is athermal efficiency of a combustor 3; Hf is a heat quantity of fuel; γ4is a specific gravity of fuel gas; Vcb is a volume of a combustor; andG4 is a flow rate of turbine inlet combustion gas (=G3+Gf). Further, G3(s), T3 (s), G4 (s), Gf (s) and Tf (s), respectively, are functions by“s,” and each is a function which varies depending on measured values.

Here, the formula (1) expresses a dynamic behavior of turbine inlettemperature; wherein, a first item of a right-hand member representsthermal energy that fuel gas owns; a second item of a right-hand memberrepresents thermal energy that air flowing in owns; a third item of aright-hand member represents thermal energy which is generated bycombustion; a fourth item of a right-hand member represents energy whichis necessary for combustion gas to be increased to reach current turbineinlet temperature T4; and a left-hand member represents an amount ofchange of thermal energy due to combustion gas versus an amount ofchange of the turbine inlet temperature T4, respectively. Consequently,when the right-hand member is positive, it means that energy beingsupplied by the combustor 3 is higher than an energy necessary to beincreased to the current turbine inlet temperature T4. On the otherhand, when the right-hand member is negative, it means that an energysupplied by the combustor 3 is lower than an energy necessary to beincreased to the current turbine inlet temperature T4.

Value of turbine inlet temperature T4 which is determined in a turbineinlet temperature operating section 15 based on a transfer function ofthe formula (2) is supplied to a pilot ratio operating section 16, abypass valve opening operating section 17 and an IGV opening operatingsection 18. Then, in the pilot ratio operating section 16, a pilot ratiois determined on the basis of FIG. 2 and supplied to a multiplicationsection 12. Additionally, in the bypass valve opening operating section17, a bypass valve control signal which is a value based on FIG. 3 isdetermined so as to be supplied to a combustor bypass valve 8. Moreover,in the IGV opening operating section 18, an IGV control signal which isa value based on FIG. 4 is determined and supplied to the IGV 5. Here,axes of abscissa in FIG. 2 through FIG. 4 represent a turbine inlettemperature T4. In other words, when the turbine inlet temperature T4becomes high, the pilot ratio becomes small; and when the turbine inlettemperature T4 exceeds a predetermined value, a change is made not onlyto close the combustor bypass valve 8 but also to open the IVG 5.

A pilot ratio determined by the pilot ratio operating section 16 in theabove-mentioned manner is supplied to the multiplication section 12; andin the multiplication section 12, the pilot ratio is multiplied by CSOthat is supplied by the limiter 11. Now, when the pilot ratio is P, apilot fuel control signal which equals to a value of P×CSO is outputfrom the multiplication section 12 and supplied to a subtraction section13 and a pilot fuel control valve 7. Because this pilot fuel controlsignal is supplied to the subtraction section 13, by subtracting thepilot fuel control signal from CSO supplied by the limiter 11 in thesubtraction section 13, a main fuel control signal which is equivalentto (1−P)×CSO is calculated from the subtraction section 12 and suppliedto the main fuel control valve 6.

By having the combustion controller 20 perform in the above-mentionedmanner, it is possible to control combustion state of a combustor 3based on the turbine inlet temperature T4. In other words, when theturbine inlet temperature T4 is high, by opening the IVG 5 as well as byclosing the combustor bypass valve 8, the flow rate of air flowing intothe combustor 3 is increased, thereby reducing the fuel-air ratio; andmoreover, by opening the main fuel control valve 6 as well as by closingthe pilot fuel control valve 7, the pilot ratio can be reduced, so as torestrain an amount of exhaust of NOx which is generated at a high loadtime.

Also, when the turbine inlet temperature T4 is low, by not only closingthe IVG 5 but also by opening the combustor bypass valve 8, it ispossible to increase the flow rate of air flowing into the combustor 3so as to increase the fuel-air ratio; and additionally, by not onlyclosing the main fuel control valve 6 but also by opening the pilot fuelcontrol valve 7, it is possible to increase the pilot ratio so as torestrain combustion vibration generating at a time of low load andachieve stable combustion.

Further, in an embodiment in accordance with the present invention, aturbine inlet temperature T4 is determined based on a transfer functionin the formula (2) in a turbine inlet temperature operating section 15.However, for example, a construction shown in FIG. 5 may be employed.The turbine inlet temperature operating section 15 shown in FIG. 5 is soconstructed as to be based on a formula (3) below. Here, in the formula(3), T4 is a present turbine inlet temperature; T4 k is a turbine inlettemperature resulting from a previous calculation; Δt is a timing whenmeasured values are supplied by measuring sections 22 through 24,respectively. In addition, the present turbine inlet temperature T4 isexpressed as a formula (4) by the formula (3).Cp4 Vcbγ4×(T4−T4k)/Δt=Cpf Gf Tf+Cp3 G3 T3+η Hf Gf−Cp4 G4 T4  (3)T 4=(( Cpf Gf Tf+Cp3 G3 T3+η Hf Gf)×Δt+Cp4 Vcbγ4×T4k)/(Δt Cp4 G4+Cp4Vcbγ4)  (4)

In FIG. 5, after fuel temperature Tf and fuel flow rate Gf aremultiplied in the multiplication section 31, fuel specific heat Cpfserving as a constant is multiplied in the multiplication section 32;and also, after air temperature T3 and air flow rate G3 are multipliedin the multiplication section 33, specific heat of casing Cp3 of thecombustor 3 serving as a constant is multiplied in the multiplicationsection 34. Further, fuel flow rate Gf is multiplied by a value η×Hfwhich is multiplied by heat efficiency η and heat quantity of fuel Hf ofthe combustor 3 serving as constants in the multiplication section 36.Then, after values obtained by the multiplication sections 32 and 34 areadded in the addition section 35, the value determined by this additionsection 35 and the value determined by the multiplication portion 36 areadded in the addition section 37.

Value (Cpf Gf Tf+Cp3 G3 T3+η Hf Gf) supplied by the addition section 37as described above is multiplied by timing A t serving as a constant inthe multiplication section 38. Moreover, a memory 30 accommodates aturbine inlet temperature T4 k resulting from the previous calculation,and when this turbine inlet temperature T4 k is supplied to themultiplication section 39, specific heat Cp4 of fuel gas serving as aconstant, volume Vcb of a combustor 3 and specific gravity γ4 ofcombustion gas are multiplied. Further, in the addition section 40,value (Cpf Gf Tf+Cp3 G3 T3+η Hf Gf)×Δt determined by the multiplicationsection 38 is added to a value determined by the multiplication section39.

Moreover, after in the addition section 41 fuel flow rate Gf and airflow rate G3 are added so that turbine inlet combustion gas flow rate G4is determined, this turbine inlet combustion gas flow rate G4 ismultiplied by a value of timing Δt serving as a constant multiplied byspecific heat Cp4 of combustion gas in the multiplication section 42.And, further, in the addition section 43, multiplication value ofspecific heat Cp4 of fuel gas serving as a constant, a volume Vcb of thecombustor 3 and specific gravity γ4 of combustion gas is added to avalue determined by the multiplication section 42.

When a value A=((Cpf Gf Tf+Cp3 G3 T3+η Hf Gf)×Δt+Cp4 Vcb γ4×T4 k)determined by an adder 40 and a value B=(Δt Cp4 G4+Cp4 Vcb γ4)determined by the addition section 43 are supplied to the subtractionsection 44, A/B is calculated so as to determine the present turbineinlet temperature T4. Then, the determined turbine inlet temperature T4is supplied to a pilot ratio operating section 16, a bypass valveopening operating section 17 and an IGV opening operating section 18,respectively, and is housed in the memory 30 as a turbine inlettemperature T4 k.

Here, a turbine inlet temperature operating section 15 is not limited toan example of construction as shown in FIG. 5, but may be constructed inother manners as long as the turbine inlet temperature T4 can bedetermined based on a function in the formula (1). Additionally, flowrate G3 of air being supplied to a combustor 3 is determined based on adifferential pressure Pd of air flowing into a compressor 1 and anopening k of a combustor bypass valve 8, but it may be measured directlyby a flow-meter which is installed to a passageway for supplying air tothe combustor 3.

INDUSTRIAL APPLICABILITY

As described above, with embodiments of the present invention, becausein a turbine inlet temperature operating section, it is possible todetermine a turbine inlet temperature based on flow rate and temperatureof fuel and air, respectively, being supplied to a combustor, it ispossible to determine a turbine inlet temperature which is relativelyclose to actual temperature. Additionally, because combustion state of acombustor is controlled based on this turbine inlet temperature, it ispossible to make a response thereof better. Moreover, different fromconventional manner, because combustion state of a combustor is notcontrolled based on a generator output, it is possible to controlcombustion state so as to always maintain it to be an optimum combustionstate, irrespective of disturbance of electric power system and a changein state of a steam turbine being mounted to a same shaft of a gasturbine.

1. A combustor controller controlling a combustor, which is mounted to agas turbine being installed to a same shaft of a generator, andsupplying the relevant gas turbine with combustion gas so as to rotateit, comprising: a fuel flow rate operating section which sets a flowrate of fuel being supplied to said combustor based on a differentialvalue between an output of said generator and an aimed output of saidgenerator; a turbine inlet temperature operating section whichdetermines a turbine inlet temperature serving as a temperature ofcombustion gas flowing into said gas turbine from said combustor basedon a flow rate and a temperature of fuel and air, respectively, flowinginto said combustor; a pilot ratio operating section which sets a pilotratio serving as a ratio of a pilot fuel, being supplied to a pilotnozzle inside said combustor that performs diffusion combustion of apilot light, versus entire fuel flow rate serving as a total of saidpilot fuel and a main fuel, being supplied to a main nozzle inside saidcombustor that performs premixed combustion by mixing air and fuel,based on a turbine inlet temperature determined by said turbine inlettemperature operating section; and an air flow rate operating sectionwhich sets a flow rate of air flowing inside said combustor based on aturbine inlet temperature determined by said turbine inlet temperatureoperating section; and is characterized by: wherein, flow rates of saidpilot fuel and said main fuel are controlled based on a pilot ratiodetermined by said pilot ratio operating section and said fuel flow ratedetermined by said fuel flow rate operating section; and wherein,combustion state of said combustor is controlled by controlling a flowrate of air flowing into inside of said combustor by air flow ratedetermined by said air flow rate operating section.
 2. A combustorcontroller as described in claim 1 is characterized by: wherein, a pilotratio calculated by said pilot ratio operating section is multiplied bya fuel flow rate determined by said fuel flow rate operating section soas to determine said flow rate of pilot fuel to said pilot nozzle;wherein, said flow rate of main fuel to said main nozzle is determinedby subtracting said flow rate of pilot fuel from said flow rate of fueldetermined by said fuel flow rate operating section; and wherein, flowrates of said pilot fuel and said main fuel are controlled bycontrolling openings of a pilot fuel control valve and a main fuelvalve, respectively, based on said flow rates of pilot fuel and mainfuel that are determined.
 3. A combustor controller as described inclaim 1 is characterized by: wherein, when air compressed by acompressor sharing a same shaft of said gas turbine is supplied to saidcombustor, an opening of an inlet guide vane being installed to saidcompressor and an opening of a combustor bypass valve being mounted to apassageway for supplying compressed air to said gas turbine, divergedfrom a passageway for supplying compressed air to said combustor fromsaid compressor are controlled based on said flow rate of air determinedby said air flow rate operating section.
 4. A combustor controller asdescribed in claim 3 is characterized by: wherein, a value of a flowrate of air being supplied to said combustor, which is to be supplied tosaid turbine inlet temperature operating section, is determined based ona differential pressure at an inlet of said compressor and an opening ofsaid combustor bypass valve.
 5. A combustor controller as described inclaim 1 is characterized by: wherein, said fuel flow rate operatingsection comprising a subtraction section which determines a differentialvalue between an output of said generator and an aimed output of saidgenerator; and a flow-rate setting portion which sets a flow rate offuel to said combustor based on a value determined by said subtractionsection; wherein, when said flow rate of fuel being set by saidflow-rate setting section is more than a predetermined threshold, saidpredetermined threshold is specified as said flow rate of fuel so as tobe supplied.
 6. A combustor controller as described in claim 1 ischaracterized by: wherein, when said turbine inlet temperaturedetermined by said turbine inlet temperature operating section is low,said pilot ratio determined by said pilot ratio operating section ishigh, and air flow rate to be determined by said air flow rate operatingsection will be increased; and wherein, further, when said turbine inlettemperature determined by said turbine inlet temperature operatingsection is high, said pilot ratio to be determined by said pilot ratiooperating section is low, and air flow rate determined by said air flowrate operating section will be decreased.
 7. A combustor controller asdescribed in claim 1 is characterized by: wherein, in said turbine inlettemperature operating section, said turbine inlet temperature T4 isdetermined by:Cp4 Vcbγ4×(dT4/dt)=Cpf Gf Tf+Cp3 G3 T3+ηHf Gf−Cp4 G4 T4 where, Gf: Flowrate of fuel to be supplied to said combustor Tf: Temperature of fuel tobe supplied to said combustor G3: Flow rate of air to be supplied tosaid combustor T3: Temperature of air to be supplied to said combustorCp3: Specific heat of casing of said combustor Cp4: Specific heat ofcombustion gas generated in said combustor Cpf: Specific heat of saidfuel η: Thermal efficiency of said combustor Hf: Heat quantity of saidfuel γ4: Specific gravity of said combustion gas Vcb: Volume of saidcombuistor G4: Flow rate of turbine inlet combustion gas (=G3+Gf).
 8. Acombustor controller as described in claim 2 is characterized by:wherein, in said turbine inlet temperature operating section, saidturbine inlet temperature T4 is determined by:Cp4 Vcbγ4×(dT4/dt)=Cpf Gf Tf+Cp3 G3 T3+ηHf Gf−Cp4 G4 T4 where, Gf: Flowrate of fuel to be supplied to said combustor Tf: Temperature of fuel tobe supplied to said combustor G3: Flow rate of air to be supplied tosaid combustor T3: Temperature of air to be supplied to said combustorCp3: Specific heat of casing of said combustor Cp4: Specific heat ofcombustion gas generated in said combustor Cpf: Specific heat of saidfuel η: Thermal efficiency of said combustor Hf: Heat quantity of saidfuel γ4: Specific gravity of said combustion gas Vcb: Volume of saidcombuistor G4: Flow rate of turbine inlet combustion gas (=G3+Gf).
 9. Acombustor controller as described in claim 3 is characterized by:wherein, in said turbine inlet temperature operating section, saidturbine inlet temperature T4 is determined by:Cp4 Vcbγ4×(dT4/dt)=Cpf Gf Tf+Cp3 G3 T3+ηHf Gf−Cp4 G4 T4 where, Gf: Flowrate of fuel to be supplied to said combustor Tf: Temperature of fuel tobe supplied to said combustor G3: Flow rate of air to be supplied tosaid combustor T3: Temperature of air to be supplied to said combustorCp3: Specific heat of casing of said combustor Cp4: Specific heat ofcombustion gas generated in said combustor Cpf: Specific heat of saidfuel η: Thermal efficiency of said combustor Hf: Heat quantity of saidfuel γ4: Specific gravity of said combustion gas Vcb: Volume of saidcombuistor G4: Flow rate of turbine inlet combustion gas (=G3+Gf).
 10. Acombustor controller as described in claim 4 is characterized by:wherein, in said turbine inlet temperature operating section, saidturbine inlet temperature T4 is determined by:Cp4 Vcbγ4×(dT4/dt)=Cpf Gf Tf+Cp3 G3 T3+ηHf Gf−Cp4 G4 T4 where, Gf: Flowrate of fuel to be supplied to said combustor Tf: Temperature of fuel tobe supplied to said combustor G3: Flow rate of air to be supplied tosaid combustor T3: Temperature of air to be supplied to said combustorCp3: Specific heat of casing of said combustor Cp4: Specific heat ofcombustion gas generated in said combustor Cpf: Specific heat of saidfuel η: Thermal efficiency of said combustor Hf: Heat quantity of saidfuel γ4: Specific gravity of said combustion gas Vcb: Volume of saidcombuistor G4: Flow rate of turbine inlet combustion gas (=G3+Gf).
 11. Acombustor controller as described in claim 5 is characterized by:wherein, in said turbine inlet temperature operating section, saidturbine inlet temperature T4 is determined by:Cp4 Vcbγ4×(dT4/dt)=Cpf Gf Tf+Cp3 G3 T3+ηHf Gf−Cp4 G4 T4 where, Gf: Flowrate of fuel to be supplied to said combustor Tf: Temperature of fuel tobe supplied to said combustor G3: Flow rate of air to be supplied tosaid combustor T3: Temperature of air to be supplied to said combustorCp3: Specific heat of casing of said combustor Cp4: Specific heat ofcombustion gas generated in said combustor Cpf: Specific heat of saidfuel η: Thermal efficiency of said combustor Hf: Heat quantity of saidfuel γ4: Specific gravity of said combustion gas Vcb: Volume of saidcombuistor G4: Flow rate of turbine inlet combustion gas (=G3+Gf).
 12. Acombustor controller as described in claim 6 is characterized by:wherein, in said turbine inlet temperature operating section, saidturbine inlet temperature T4 is determined by:Cp4 Vcbγ4×(dT4/dt)=Cpf Gf Tf+Cp3 G3 T3+ηHf Gf−Cp4 G4 T4 where, Gf: Flowrate of fuel to be supplied to said combustor Tf: Temperature of fuel tobe supplied to said combustor G3: Flow rate of air to be supplied tosaid combustor T3: Temperature of air to be supplied to said combustorCp3: Specific heat of casing of said combustor Cp4: Specific heat ofcombustion gas generated in said combustor Cpf: Specific heat of saidfuel η: Thermal efficiency of said combustor Hf: Heat quantity of saidfuel γ4: Specific gravity of said combustion gas Vcb: Volume of saidcombuistor G4: Flow rate of turbine inlet combustion gas (=G3+Gf).